The 69ft (21 metre) tall building in the parish of Vale is on sale with a guide price of £2.95m.

The property - renamed The Lookout - is available through the island’s open market, which means it can be bought by anyone who has a British passport or the right to reside in the UK.

Planning permission has been granted for the property to be turned into a six-floor four-bedroom home – complete with an underground extension, observation deck, terrace, floating sunroom and walkways around an adjoining water-filled quarry.

The original structure of Vale Mill was built out of wood in 1770, before being rebuilt in granite in 1854. It operated as a flour windmill until the German occupation of 1940, when it was used as an observation tower. It was gifted to the island’s government – the States of Guernsey – in 1968 and sold into private ownership 40 years later after falling into disrepair.

The Lookout was the first property to be added to Guernsey’s open market under a new ‘exceptional circumstances’ rule that was agreed last year.

The changes were introduced by the States of Guernsey to sensitively increase the size of the open market, while at the same time encourage the development of homes and preserve buildings that are of historic significance and form part of the island’s cultural heritage.

Savills provided consultancy advice during the open market application process and Nick Paluch, director in the Guernsey office residential sales team, said the sale represented a rare opportunity.

“The Lookout promises to be a landmark property – something that’s unique to the open market and offering exactly the sort of diversity that’s needed if Guernsey is to continue to attract new investment," he said. "It’s an iconic building that can be seen across the island and a real opportunity for someone to create a ‘Grand Designs’ style home of the highest quality.

“Guernsey continues to be a popular destination for would-be buyers and we have seen strong levels of activity since the start of the year. The beautiful scenery and outdoor lifestyle are complemented by a growing reputation as a centre of excellence for business and finance, together with a strong community feel, some excellent schools, low crime rates and favourable tax regime.”

James Ridout, director of Vale Mill Limited, whose father bought The Lookout at auction in 2008 with a business partner, has restored the building to prepare the site for further development.

The works have included repointing the stonework of the mill and ensuring the structure is wind and water tight, as well as adding staircases and clearing and landscaping the land around the quarry.

“It’s taken a lot of hard work and perseverance to get to this point – and it’s not been without its challenges – but we’re now in a position where we feel the mill and surrounding site are ready to be taken to the next stage,” James said.

“The open market listing is hugely important and will hopefully attract the level of investment needed to ensure the exciting plans for the mill can come to fruition – preserving a historically and culturally important building and creating a modern state-of-the-art home of which Guernsey can be proud.

“There’s nothing like it on the island. It’s a one-of-a-kind property and the views from the top of the tower are beyond compare. They’re the best in Guernsey. You can see out to sea for miles around.”

Planning permission was granted in 2020 for conversion of the mill into a four-bedroom home with a kitchen/dining area, utility room and breakfast room along with a substantial basement extension, cantilevering out over the quarry.

The top two former German observation levels would be used for possible office or entertaining areas.

The cantilevered extension would be constructed within the rock face of the quarry, built to blend with the mill along with large windows opening onto a balcony deck.

It would be connected to the mill by an underground link, which will run under the driveway between the mill and the quarry. There are also plans for a walkway from the main house towards a floating summer house.